In recent years, there has been an increasing demand for new sources of protein, both for human and animal nutrition. In addition to alternative sources of protein, such as algae or edible insects, protein obtained from yeast and mold biomass is becoming more and more important. The main fungal protein producers are the yeasts Saccharomyces cerevisiae, Kluyveromyces marxianus, Candida utilis, Yarrowia lipolytica, and the molds Fusarium venenatum, Aspergillus oryzae, and Monascus purpureus. The production of fungal protein has many advantages, including the ability to regulate the amino acid composition, high protein content in dry matter, the possibility of production in a continuous process, independence from climatic factors, and the possibility of using waste substrates as ingredients of media. One of the disadvantages is the high content of nucleic acids, which generates the need for additional purification procedures before use in food. However, a number of enzymatic, chemical, and physical methods have been developed to reduce the content of these compounds. The paper presents the current state of knowledge about fungal producers, production and purification methods, the global market, as well as opportunities and challenges for single-cell protein (SCP) production.

Pumpkin is a highly nutritious plant, rich in valuable nutrients that benefit human health. Due to the high perishability of this fruit, the production of pumpkin juice is a practical way to use it effectively. Recently, fermented vegetable juices have been used as a dairy alternative due to their nutritional and potential probiotic properties. This study investigated the fermentation of pumpkin juice using different strains of lactic acid bacteria (LAB), with and without heat treatment. The effects of fermentation on microbial growth, pH, acidity, extract, sugars, carotenoids, polyphenols, and antioxidant properties were analyzed. The heat-treatment process did not greatly impact the dry matter content, pH, acidity, extract, or sugar content. However, it led to a reduction in carotenoid and polyphenol levels. During fermentation, there was a consistent decrease in pH and an increase in total acidity, with no noticeable differences between bacterial strains regarding their influence on these parameters. The study revealed that there were no distinctions between LAB strains in their effects on pH, acidity, and carotenoid content in fermented pumpkin juice. Nonetheless, both L. sakei and L. plantarum proved to be effective in the fermentation process, with L. sakei demonstrating greater adaptability. The expected pH, acidity, and sugar content changes were consistently observed throughout the fermentation process. Overall, results confirm the efficacy of the used Lactobacillus strains in fermenting pumpkin juice and highlight the potential impact of heat treatment on the nutritional composition of the juice. The purpose of thermal processing of pumpkin juice, which is conducted with lactic acid fermentation, is crucial for the food industry. It extends the product’s shelf life, improves its nutritional and taste profiles, and guarantees its microbiological safety.

Lactic acid fermentation has emerged as a promising strategy to enhance the functional and health-promoting qualities of plant-based foods. This study evaluates the impact of lactic acid fermentation on the antioxidant capacity, microbial viability, and chemical stability of freeze-dried peaches, aiming to develop a functional food with probiotic potential. Two bacterial strains—Fructilactobacillus fructivorans (P_FF) and Lactiplantibacillus plantarum (P_LP)—were used to assess strain-dependent effects on microbial and bioactive compound profiles. Microbiological analyses included total viable count (TVC), fungal count (TFC), and total lactic acid bacteria (TCLAB). Chemical analyses comprised polyphenol, flavonoid, anthocyanin, carotenoid, sugar, and vitamin C content, as well as antioxidant activity (DPPH, ABTS, reducing power). Thermal and structural stability were examined via thermogravimetric analysis (TGA) and Fourier-transform infrared spectroscopy (FTIR). Fermentation significantly increased the counts of lactic acid bacteria, achieving 8.38 and 7.86 log CFU/g after freeze-drying, respectively. While total polyphenols slightly decreased (by 9.5% and 1.1% for L. plantarum and F. fructivorans, respectively), flavonoid content increased notably by 16.1% in F. fructivorans-fermented samples. Antioxidant activities, assessed by ABTS and DPPH assays, were largely maintained, although a reduction in reducing power was observed. Additionally, fermentation led to sucrose hydrolysis, resulting in higher glucose and fructose contents, and increased water content in the final products. Minor increases in total fungal counts were noted after freeze-drying but remained within acceptable limits. Overall, the combination of fermentation and freeze-drying processes preserved key antioxidant properties, enhanced microbial safety, and produced functional peach-based products with improved bioactivity and extended shelf life. These findings highlight the potential of fermented freeze-dried peaches as innovative, health-oriented alternatives to traditional fruit snacks.

The snack market is shifting toward healthier options, leading to a growing interest in organic snacks. Dried fruits are particularly popular due to their long shelf life and convenience. Freeze-drying helps preserve both the taste and nutrients of these fruits. Among them, peaches are noteworthy for their antioxidant and anti-inflammatory properties. The research assessed the impact of lactic fermentation using Lactiplantibacillus plantarum (P_LP) and Fructilactobacillus fructivorans (P_FF), followed by freeze-drying, on the physicochemical, structural, and sensory properties of peach slices. Fermentation increased acidity (>22 mg/kg), decreased sugars (up to 43.5%), and raised salt content (to ~0.5%), effectively altering the fruit’s chemical profile. Dry matter content decreased by 6.0% (P_LP) and 7.2% (P_FF), while water activity remained low (0.13–0.15). Color parameters changed notably: L* values decreased, and a* values increased, with total color differences (ΔE) exceeding 15. Structural changes included higher porosity (to 71.4% in P_LP and 72.8% in P_FF) and reduced hardness from 50.1 N (control) to 35.7 N (P_LP) and 28.2 N (P_FF), which may benefit processing. Water sorption isotherms suggested improved stability under elevated humidity. However, sensory analysis showed lower consumer acceptance of the fermented samples due to reduced sweetness, crunchiness, and overall palatability, along with undesirable flavors from F. fructivorans. While lactic fermentation holds the potential for creating fruit snacks with better functional value, further optimization is needed to enhance sensory appeal and market potential.